Few words mean less today than “genius,” which casual overuse has seriously devalued over time. Like “brilliant” and “awesome,” “genius” is cheap praise, and too often it is mistaken for simple intelligence. That’s why I humphed noisily and rolled my eyes when I overheard some woman say that the man whose performance we were about to see — one Rinde Eckert — was indeed “a genius.”

Honey, there ain’t no such thing.

Mastermind · Rinde Eckert reprises his Obie Award-winning role of Nathan, a brilliant piano tuner trying to finish his operatic adaptation of Moby Dick before he loses his mind, in And God Created Great Whales. Singer and actress Nora Cole also reprises her role as Nathan’s muse. - Nathaniel Gonzalez | Daily Trojan

Or is there? In less than 80 minutes, Eckert makes a frightfully compelling case. Some have powers of mind; others have ones of body. Eckert, miraculously, was gifted with both. It is a rare privilege to behold.

Eckert’s And God Created Great Whales, which was shown Thursday and Friday at the wonderfully dilapidated 24th Street Theatre, is the highest kind of performance art — crazily ambitious, deeply felt and occasionally sublime. But mostly, it’s ineffable. Words are rarely enough.

Eckert plays Nathan, an aging piano tuner trying desperately to finish a colossal undertaking — turn Herman Melville’s notoriously stylized novel Moby Dick into an opera — before his diseased mind goes blank forever. Nathan wakes up every morning at his old piano with fewer and fewer memories, but surrounded by color-coded tape recorders, notebooks, scores, flash cards and sticky notes. With these objects, he is able to piece together his life and continue writing the opera.

To inspire his creative efforts, as well as to keep him from permanently going under, Nathan enlists the help of a muse (Nora Cole). Of course, this muse, as Nathan’s own tape-recorded voice tells him each morning, is the product of Nathan’s deranged imagination made in the image of his lifelong love, famous opera singer Olivia Walsh. The muse carries the plot — both of the show and of Nathan’s opera — constantly getting Nathan back on track as his seagoing mind begins to wander to strange places.

Each day is an uphill battle against time. Nathan completes less and less of his work as his condition worsens. Sometimes, he even has to relearn how to speak. His muse is his rock, anchoring him to an increasingly precarious reality. But as Nathan goes, she goes. Time, like Melville’s great white whale, is relentless.

Eckert’s performance — think of an operatic John Malkovich, with resonances of Russell Crowe’s Professor Nash from A Beautiful Mind — nearly engulfs the room, even in his quieter moments. He can convey great feeling with the simplest gesture; no stagy facial exaggerations here. Elation is but a smile; longing, but one far-off glance. And when he sings — whether in rich baritone, arms fully extended, or vulnerable falsetto, hunched painfully over — nothing can stop him.

In perhaps an even greater feat, Cole matches Eckert’s incandescence. Had she been a lesser performer, the show would not have worked, for Eckert and Cole play essentially the same inseparable person, but they are also — and crucially — worlds apart. She is the lighthouse to his ship, the shore to his sea. Neither can exist without the other.

Cole plays her opera diva to perfection. Heaven’s gates are flung wide when she opens her mouth. With piercing vibrato, and inhumanly high notes, she does the Muses proud.

If it’s possible, Eckert and Cole are even better together, which is as it should be. Weak harmonization often spoils great productions; not so with these world-class artists. Theirs is effortless.

Eckert’s script is beautifully written, carrying with it a feeling of incompletion that mirrors Nathan’s own state of mind. Big ideas like madness, memory and mortality are treated seriously, but never didactically. But it isn’t all weighty stuff. Lighter moments — Cole has an especial gift for comedy — are served up in near-equal measure, as when Cole plays the various street vendors selling whale-bone corsets and shark-tooth earrings.

The stage design, like David Schweizer’s direction, gives us only the bare necessities, and to great effect. Everything — the muse’s perch of old boxes and Nathan’s piano — are held in place with rope, giving the stage a ship-like feel. The backdrop, a billowy white sheet, can, with Kathi O’Donohue’s basic lighting, be either a blood-stained sea or a cool-blue sky.

In the end, few shows are as good and few men are as visionary as And God Created Great Whales and Eckert.

“Consciousness is what defines genius,” writes prominent literary critic Harold Bloom.

Genius, in other words, expands man’s collective mind, and brings it to unfathomable places. Eckert proves Bloom right.